This research project on visual perceptual processes in aging focuses on object perception. The initial research will examine whether the basic mechanisms of object perception are the same for young and old adults. A pilot study suggests that they are, although they may differ in detail. The research will explore two areas in which the detail may differ. The first is the nature of the basic perceptual elements from which objects are formed. The second is in the processes by which those perceptual features are combined to form objects. The investigations of Anne Treisman and coworkers of object perception mechanisms in young adults provides much of the theory and methodology of the proposed experiments. Their work has capitalized on a basic phenomenon. A target stimulus which has a feature not shared by distracting stimuli will "pop out" of the distractors, whereas a target which does not have a unique feature, but which shares features with the distractors, must be searched for with the expenditure of considerable congnitive effort. In one set of experiments, several search techniques which capitalize on the "pop out" phenomenon will be used to identify some features which might change with aging. Others sets of experiments will focus on the processes by which features are combined to form objects. Because attention has been shown to be important to some of the combination processes, these experiments are designed to characterize the changes which reduced attentional capacity is likely to produce. One such set of experiments will look for possible reductions in the number of items which can be searched as a group. Some general perceptual organizational processes are also known to influence the grouping of features into objects. Another set of experiments will examine the stability of those organizational processes with aging. Finally, other cognitive factors have been shown to influence object perception in younger adults. A set of experiments will examine whether cognitive changes in aging modify these organizational influences on object perception. The proposed program of research will help characterize the extent to which and in what circumstances older adults have difficulty with object perception. It will help identify special situations in which older adult may be at a disadvantage. The research can also contribute to the formulation of guidelines for presenting visual information effectively to older adults.